Intermountain West of the United States: Our research in the western United States has documented that the warming experienced by sub-alpine lakes in the Sierra Nevada, Snake Range, Ruby and East Humboldt Mountains and the Uintas, during the late 20th and early 21st centuries is unprecedented in the context of the last ~ 150 years (Porinchu et al. 2007; Porinchu et al. 2010; Reinemann et al. 2011; Reinemann et al. 2014a). We are extending these records further into the past, i.e. the middle to late Holocene, to develop high resolution (multi-decadal-scale) reconstructions of Great Basin paleoclimate over a longer time-scale, put contemporaneous changes into context, and increase our understanding of the linkage between these localized changes and regional climate dynamics. Together with Stephen Cooper (M.S. student, UGA) and colleagues at Ohio University and The Ohio State Unviersity we have also recently begun a project to use pollen, charcoal and geochemical signals extracted from meadow sediment cores to develop lengthy, high-resolution (multi-decadal to sub-centennial scale) fire and vegetation histories for Great Basin National Park.
Front Range, Colorado Rockies: We have increasingly become interested in using stable isotopes of C and N in bulk lake sediment and stable isotopes of O extracted from subfossil chironomid remains to address how high elevation aquatic ecosystems are responding to elevated air temperature and hydroclimate variability in recent decades. I am particularly interested in characterizing how the retreat of small alpine glaciers, in response to altered temperature and precipitation regimes, will impact thermally sensitive aquatic invertebrates and aquatic communities. Danielle Haskett, (Ph.D. candidate, UGA), is currently working on a project reconstructing recent and long-term climate and environmental variability in Rocky Mountain National Park, specifically focusing on episodes of sustained and rapid warming during the late Quaternary, i.e the late 20th and early 21st centuries and the Pleistocene-Holocene transition.
Cordillera de Talamanca, Costa Rica: This project is designed to address questions related to the temporal variability in thermal conditions characterizing Costa Rica during the Holocene (last 10,000 years). Using surface sediment collected by our collaborator, Dr. Sally Horn (University of Tennessee), Jiaying Wu (Ph.D. candidate, UGA) documented the modern distribution of sub-fossil midges in this region; developed a midge-based surface water temperature inference model (Wu et al. 2015); and reconstructed late Holocene thermal conditions for the region (Wu et al. 2016). Jiaying is currently working on: 1) identifying whether elevated temperatures played a role in exacerbating wide-spread, regional droughts and wildfires in Costa Rica during the Medieval Climate Anomaly (~ 700-1250 CE); 2) quantifying the geographic extent and magnitude of thermal fluctuation associated with an abrupt climate event that occurred 5200 years BP; and 3) determining if these climate events coincided with structural changes in ancient civilizations (e.g. the Maya) or landscape change in the tropical highlands of Central America.